The fruit of the coffee plant (e.g., Coffea arabica) is often called the “coffee cherry.” The coffee cherry is made up of the following layers (from the outside in): skin, pulp, mucilage, parchment, and bean. The skin, also referred to as the epicarp or exocarp, is a monocellular layer covered with a waxy substance ensuring protection of the fruit. The mesocarp includes the pulp and the mucilage. The pulp is the fleshy outer layer of the mesocarp, directly beneath the skin, which during processing can be removed with a pulping machine. The mucilage is the slimy layer found between the pulp and parchment, adhering to the parchment inside a coffee cherry. It is generally not removed by pulping. Mucilage is not present in unripe coffee fruit, and disappears in overripe coffee. The endocarp, or “parchment,” is the tough integument tightly pressed to the bean when fresh but from which the bean shrinks during drying. It lies between the fleshy part (or pulp) of the cherry and the silver skin. The endocarp also includes the thin, crumbly paper-like covering that is left on wet-processed coffee beans after pulping and fermentation, and which is subsequently removed during hulling. The bean includes the endosperm and the embryo. The endosperm includes the tissues that feed the embryo during germination. The embryo ultimately forms the coffee beans. The silver skin is the seminal integument covering the endosperm, i.e., the thin, papery, shiny layer immediately surrounding the coffee bean, being the remnant of the integument. During processing, milling before export removes most silver skin, and the remainder is removed during roasting in the form of chaff. The endosperm fills the integument as the coffee cherry ripens.
The coffee cherry is harvested and processed to make coffee. During processing, the bean portion of the cherry is removed and further processed using various techniques. This processing generally removes the bean, silver skin and parchment. Thus, after the bean is removed, a significant amount of the coffee cherry fruit remains.
Traditionally, the portion of the cherry remaining after the bean is removed is viewed as waste, although it is sometimes processed into compost or animal feed. However, this remaining portion has significant nutritive value. In particular, it is high in antioxidants and polyphenols, including chlorogenic acids of various types, caffeic acid, quinic acid, ferulic acid, proanthocyanidins, and others. These compounds have antioxidant activity, which can contribute to good heath by reducing oxidative injury and thus ameliorating associated disease states such as diabetes, Alzheimer's disease, and certain types of cardiovascular and neurological conditions. The beneficial anti-oxidative and other properties of such compounds, as well as other beneficial components of the extracts, can also be used to treat other conditions such as skin disorders and the like. Isolating these antioxidants and other beneficial compounds from the de-beaned coffee cherry can be difficult, however. For example, coffee pulp contains high levels of tannins, which bind the protein and make it difficult to extract and precipitate. An additional problem is that the free phenols in coffee pulp become oxidized to quinones. Quinones are oxidizing agents that may oxidize amino acids in coffee cherry proteins. Also, ripe coffee fruit is used during husking, and exposure to oxygen, and also the activity of enzymes, sugars, and other components of the coffee cherries, can cause rapid degradation and/or oxidation of these compounds and rapid bacterial growth either prior to or during processing. These degradative processes can begin almost immediately following removal of the bean. As a result, currently available methods of isolating the beneficial components from coffee cherries have frequently resulted in poor yields and the presence of undesirable side-products.
As such, there remains a need in the art for improved methods of isolating antioxidants and other beneficial compounds from coffee cherries and antioxidant-rich products and compositions made from coffee cherries. The present invention satisfies these needs and provides related advantages as well.